Year	Number of Years
1960-01-01	32.035
1961-01-01	32.317
1962-01-01	32.651
1963-01-01	33.050
1964-01-01	33.523
1965-01-01	34.076
1966-01-01	34.711
1967-01-01	35.417
1968-01-01	36.178
1969-01-01	36.985
1970-01-01	37.824
1971-01-01	38.685
1972-01-01	39.556
1973-01-01	40.429
1974-01-01	41.293
1975-01-01	42.146
1976-01-01	42.989
1977-01-01	43.827
1978-01-01	44.660
1979-01-01	45.483
1980-01-01	46.293
1981-01-01	47.087
1982-01-01	47.860
1983-01-01	48.603
1984-01-01	49.308
1985-01-01	49.958
1986-01-01	50.537
1987-01-01	51.042
1988-01-01	51.476
1989-01-01	51.849
1990-01-01	52.176
1991-01-01	52.481
1992-01-01	52.786
1993-01-01	53.110
1994-01-01	53.461
1995-01-01	53.844
1996-01-01	54.254
1997-01-01	54.676
1998-01-01	55.097
1999-01-01	55.513
2000-01-01	55.924
2001-01-01	56.329
2002-01-01	56.732
2003-01-01	57.132
2004-01-01	57.527
2005-01-01	57.914
2006-01-01	58.289
2007-01-01	58.648
2008-01-01	58.991
2009-01-01	59.316
2010-01-01	59.622
2011-01-01	59.911
2012-01-01	60.187
2013-01-01	60.452
2014-01-01	60.707
2015-01-01	60.954
2016-01-01	61.193